Effect of SiO2 on the expression of MMP-9 and TIMP-1 in human alveolar macrophages in vitro / 中华劳动卫生职业病杂志

ABSTRACT

<p><b>OBJECTIVE</b>To study the effect of SiO(2) on the expression of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) in human alveolar macrophages (AMs) associated with the pathogenesis of silicotic fibrosis.</p><p><b>METHODS</b>AMs were collected from a silicotic patient by bronchoalveolar lavage, and exposed to SiO(2) (50 microg/ml), and cultured in DMEM without serum for different time (2, 6, 12, 18, 24, 36 h). Immunocytochemical method was used to detect the level of expression of MMP-9 and TIMP-1 in AMs.</p><p><b>RESULTS</b>The expression of MMP-9 in AMs exposed to silica was up-regulated, and reached the peak at 18 h [average optical density: (0.440 +/- 0.021) vs (0.390 +/- 0.011), P < 0.05]. After that, the expression reduced markedly. However, the expression of TIMP-1 of AMs were not significantly different from the control group [average optical density: (0.175 +/- 0.019) vs (0.162 +/- 0.044), P > 0.05].</p><p><b>CONCLUSION</b>SiO(2) could induce up-expression of MMP-9 in AMs. Degradation of basement membrane by MMP-9 produced by AMs at early stage of lung injury may associate with the immigration of various cells including lung fibroblasts into the injured region.</p>